S12实时时钟实验，S12的另一个实现时间基准的程序，可配合脉冲累加器测频等。-S12 Real-Time Clock test, S12, another realization of the program time base can be measured with the pulse frequency and accumulator.

清华大学S12的单片机timer 模块的例子，通过学习，掌握基本的实时中断-RTI ACCORDING TO